IMPORTANT I have recently dug this out of a box and tried to regulate 9v from an RC car battery, it did work, but then there was a puff of smoke and it became extremely hot. This may be because i have previously fried the regulator, but i thought i would let you all know so you can be careful. I may need some filtering capacitors, not sure. please tell me if you have any ideas.
This is the circuit for converting a 12V car supply to 4.5V.
You will need:
2 X 2 wire PCB mounted terminal blocks (optional)
1 X diode
1 X L78S05CV voltage regulator chip
Some verro board
Step 1: Connect the Terminal Blocks
Drill a hole to break the tracks and solder the two terminal blocks as shown in the picture.
Step 2: Connect the wire jumps
Solder the jump wires in.
Step 3: Connect the Diode
Solder the diode in over the break in the tracks.
Step 4: Solder in the voltage regulator
Solder the voltage regulator in (bend it down so it's flat if space is an issue).
Step 5: Test
Connect the power into the input end of the board. Test between the connections at the other end and it should read the voltage the chip is set for.